String方法

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subString():

str＝str.substring(int beginIndex);截取掉str从首字母起长度为beginIndex的字符串，将剩余字符串赋值给str；

str＝str.substring(int beginIndex，int endIndex);截取str中从beginIndex开始至endIndex结束时的字符串，并将其赋值给str;

2：valueOf()

//byte ,short ,char ,int ,long ,float,double,booleanpublic static void main(String[] args){boolean b = true;char c = 'h';char[] cs = new char[]{'c','h','e','n'};char[] cs2 = new char[]{'t','o','d','a','y'};double d = 3;float f = 1;int i = 3;long l = 3L;Integer in = new Integer(666);System.out.println("--boolean--"+String.valueOf(b));System.out.println("--char--"+String.valueOf(c));System.out.println("--char[]--"+String.valueOf(cs));System.out.println("--double--"+String.valueOf(d));System.out.println("--float--"+String.valueOf(f));System.out.println("--int--"+String.valueOf(i));System.out.println("--long--"+String.valueOf(l));System.out.println("--object--"+String.valueOf(in));System.out.println("--char[]--"+String.valueOf(cs2, 1, 2));}

输出结果：

--boolean--true--char--h--char[]--chen--double--3.0--float--1.0--int--3--long--3--object--666--char[]--od

3：trim()

public static void main(String[] args){String s = "  nnfn  ";System.out.println("前、length: " + s);System.out.println("前、length: " + s.length());s.trim();System.out.println("中、length: " + s);System.out.println("中、length: " + s.length());s = s.trim();//赋值才改变System.out.println("后、length: " + s);System.out.println("后、length: " + s.length());}

输出结果：

前、length:   nnfn  前、length: 8中、length:   nnfn  中、length: 8后、length: nnfn后、length: 4

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